For my final co-op term, I worked for the Performance team at Yelp. I learned a lot at Yelp and really enjoyed my experience there. The culture is quite chill, and the workload is very reasonable.
During my term, there was a large group of (30 or so) Waterloo interns, and the company organized group events for us once or twice a week. These events were a good way of getting to know people. Another perk is they provide a housing search service, so you don't have to spend hours combing through Craigslist -- this proved to be super useful. There is only free lunch on Fridays, but the pantry is stocked generously with snacks and drinks. I would definitely recommend working here!